The problem is that the main support for evolution seems to be "if a wizard didn't do it, it had to be like this," and science by definition assumes a wizard didn't do it, and then the assumption tends to be forgotten. It can't deal with the possibility that a wizard did do it, but that doesn't mean that's impossible. It's not religion; serious ID proponents never advocate for any specific god or gods, only the possibility that some intelligent entity, the possibility of which science doesn't currently consider, had something to do with this. Many IDers believe in evolution, but think that it had to be set up intentionally.
Richard Dawkins, probably the most prominent atheist of our time, has said that he thinks there's a very real possibility that life on Earth was engineered by aliens, who themselves came about naturally (or from other aliens who came about naturally, etc.). ID basically takes that idea a step further -- we were engineered by someone who never came about at all, or who's from an alternative plane of reality we haven't studied yet, or something. ID isn't a theory, it's a different way of looking at things, an alternative starting point from which theories can come. ID considers the possibility that there are one or more intelligent beings who designed the universe and are not part of the universe. It's probably not science, at least by current definitions (although there are ideas in metaphysics that resemble it), but it's saying that if science is going to have the role it has in public life today, the ultimate absolute reality-determinator, then it's irresponsible for it not to consider all possibilities of truth. It either needs to broaden its view or scoot over and let other fields of study, including philosophy, discover truth too.
Honestly, I'm not sure if that really represents what IDists believe, but it's the way I see it (don't worry, I already know I'm wrong). You guys can just substitute "CE7's crazy ideas" for "ID" if it makes you feel better. And incidentally, I'm not very happy with the idea of the federal government running schools at all, but that's (mostly) a debate for another day.